Different blog use, different participation

Though it seems to be more popular for most people to discuss some issues with their friends on the micro blogs such as Twitter or community websites such as Facebook, there is still a doubt that these websites would play a role to facilitate civic engagement or promote the frequency for talking about public affairs. It is said that the success of Obama‟s case did intrigue politicians‟ attention for the effect of blog in Taiwan. That is why the study should be traced to the experiences of blog in America. There are some surveys which improved that the number of blogs have grown since 2001(Levy, 2002; Henning, 2003). In this case, Wallsten (2007) indicated that political blogs seems to have been grown faster than other types of blogs. In order to find the relationship between blog use and political participation, this study will focus on political blogs. Researchers pointed that the role of blog has become an open forum for users to address issues(Bruns, 2006; Cristol, 2002; Wall, 2006) and some researchers further claimed that blogs have been portrayed as political outlets (Kerbel and Bloom, 2005; Sweetser and Kaid, 2008; Trammell et al., 2006b) where allow users to express their self-perspective and access to different perspectives on an issue (Herring et al., 2004; Trammell and Keshelashvili, 2005; Papacharissi, 2004; Thompson, 2003). In brief, blog users also play a key role in the blog world. For this reason, the study will explore the connotation of blog users and further examine the relationship between blog use and political participation. But it seems to be less studies about types of blog users that could assess the effects of communication on blogs more precisely. To target more real supporters, this article will categorize the types of users into three kinds and measure the extent to their separate behavior which linked to political participation. --

A numerical study of ENO and TVD schemes for shock capturing

The numerical performance of a second-order upwind-based total variation diminishing (TVD) scheme and that of a uniform second-order essentially non-oscillatory (ENO) scheme for shock capturing are compared. The TVD scheme used is a modified version of Liou, using the flux-difference splitting (FDS) of Roe and his superbee function as the limiter. The construction of the basic ENO scheme is based on Harten, Engquist, Osher, and Chakravarthy, and the 2-D extensions are obtained by using a Strang-type of fractional-step time-splitting method. Numerical results presented include both steady and unsteady, 1-D and 2-D calculations. All the chosen test problems have exact solutions so that numerical performance can be measured by comparing the computer results to them. For 1-D calculations, the standard shock-tube problems of Sod and Lax are chosen. A very strong shock-tube problem, with the initial density ratio of 400 to 1 and pressure ratio of 500 to 1, is also used to study the behavior of the two schemes. For 2-D calculations, the shock wave reflection problems are adopted for testing. The cases presented in this report include flows with Mach numbers of 2.9, 5.0, and 10.0

Streaming Complexity of Spanning Tree Computation

The semi-streaming model is a variant of the streaming model frequently used for the computation of graph problems. It allows the edges of an n-node input graph to be read sequentially in p passes using Õ(n) space. If the list of edges includes deletions, then the model is called the turnstile model; otherwise it is called the insertion-only model. In both models, some graph problems, such as spanning trees, k-connectivity, densest subgraph, degeneracy, cut-sparsifier, and (Δ+1)-coloring, can be exactly solved or (1+ε)-approximated in a single pass; while other graph problems, such as triangle detection and unweighted all-pairs shortest paths, are known to require Ω̃(n) passes to compute. For many fundamental graph problems, the tractability in these models is open. In this paper, we study the tractability of computing some standard spanning trees, including BFS, DFS, and maximum-leaf spanning trees. Our results, in both the insertion-only and the turnstile models, are as follows. Maximum-Leaf Spanning Trees: This problem is known to be APX-complete with inapproximability constant ρ ∈ [245/244, 2). By constructing an ε-MLST sparsifier, we show that for every constant ε > 0, MLST can be approximated in a single pass to within a factor of 1+ε w.h.p. (albeit in super-polynomial time for ε ≤ ρ-1 assuming P ≠ NP) and can be approximated in polynomial time in a single pass to within a factor of ρ_n+ε w.h.p., where ρ_n is the supremum constant that MLST cannot be approximated to within using polynomial time and Õ(n) space. In the insertion-only model, these algorithms can be deterministic. BFS Trees: It is known that BFS trees require ω(1) passes to compute, but the naïve approach needs O(n) passes. We devise a new randomized algorithm that reduces the pass complexity to O(√n), and it offers a smooth tradeoff between pass complexity and space usage. This gives a polynomial separation between single-source and all-pairs shortest paths for unweighted graphs. DFS Trees: It is unknown whether DFS trees require more than one pass. The current best algorithm by Khan and Mehta [STACS 2019] takes Õ(h) passes, where h is the height of computed DFS trees. Note that h can be as large as Ω(m/n) for n-node m-edge graphs. Our contribution is twofold. First, we provide a simple alternative proof of this result, via a new connection to sparse certificates for k-node-connectivity. Second, we present a randomized algorithm that reduces the pass complexity to O(√n), and it also offers a smooth tradeoff between pass complexity and space usage.ISSN:1868-896